Faculty Collaboration Database

Cell free DNA testing-interpretation of results using an online calculator. Am J Obstet Gynecol 2015 Jul;213(1):30.e1-30.e4

Date

05/10/2015

Pubmed ID

25957020

DOI

10.1016/j.ajog.2015.05.004

Scopus ID

2-s2.0-84937525457 (requires institutional sign-in at Scopus site)   16 Citations

Abstract

All pregnant women, regardless of age, should be offered screening or invasive testing for chromosomal abnormalities at <20 weeks' gestation. Noninvasive prenatal screening for fetal aneuploidy with the use of cell-free DNA (cfDNA) is a screening method that offers high sensitivity and specificity in validation studies and has reduced the need for unnecessary invasive procedures. Laboratories often advertise and report a test's sensitivity and specificity as a means to describe the test's accuracy. The positive predictive value (PPV) of a screening test (the proportion of positive results that are truly positive) is a function of the prevalence of the condition in a population and often is not reported in direct-to-patient advertising. False-positive cfDNA screening tests have been reported, and there is evidence that some women are deciding to terminate their pregnancy without confirmatory testing. We believe that laboratories should disclose the patient-specific PPV of cfDNA screening for aneuploidy on result reports. To assist with counseling patients about the benefits, risks, and limitations of aneuploidy screening with the use of cfDNA and to demonstrate the relationship between an a priori risk and PPV, we developed a web-based calculator to estimate the PPV of the 4 commercially available cfDNA testing platforms for which data have been published. Estimates are made with the use of a patient's age and gestational age-related risk of trisomy 21, 18 and 13 or an a priori risk that is based on other findings. This web-based calculator is an aid for providers and genetic counselors to illustrate the relationship between disease prevalence and a test's PPV. It has enhanced our counseling of patients both before they elect noninvasive prenatal screening and after they receive a positive result.

Author List

Grace MR, Hardisty E, Green NS, Davidson E, Stuebe AM, Vora NL

Author

Emily Davidson MD Associate Professor in the Obstetrics and Gynecology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Aneuploidy
Cell-Free System
Chromosome Aberrations
Cytogenetic Analysis
Female
Humans
Pregnancy
Prenatal Diagnosis
Sensitivity and Specificity